Field of the Invention
The present disclosure relates to cleaning blades, image forming apparatuses, and process cartridges.
Description of the Related Art
Hitherto, electrophotographic image forming apparatuses transfer a toner image formed over an image bearer (hereinafter may also be referred to as “photoconductor”, “electrophotographic photoconductor”, or “electrostatic latent image bearer”) onto a recording medium or the like and then remove any unnecessary toner and other unnecessary matters (residues) remaining over the surface of the image bearer with a cleaning unit. Cleaning blades including a flat-plate-shaped elastic member made of, for example, a polyurethane rubber and a supporting member to which one end of the elastic member is secured are often used as the cleaning unit because cleaning blades can achieve an excellent cleaning performance with a simple configuration.
When a polymerization toner formed by a polymerization method or the like and having a small particle diameter and a nearly spherical shape is used instead of a typical pulverization toner in order to meet a recent need for a higher image quality, a cleaning failure may occur because the polymerization toner slips through a slight gap formed between the elastic member and the image bearer. When a contact part at which the elastic member contacts the image bearer at a free end side of the elastic member is brought into contact with the image bearer with a high pressure in order to suppress the cleaning failure, a high friction develops between the contact part and the image bearer to cause the contact part to curl, leading to a problem that a local crack (local wear) is likely to occur in an end surface of the elastic member at the free end side of the elastic member.
To overcome this problem, the present applicant has already proposed a cleaning blade in which a contact part of an elastic member made of a polyurethane rubber is impregnated with a curable composition such that the contact part can be prevented from curling (see, e.g., Japanese Unexamined Patent Application Publication No. 2014-142597).
Because the cleaning blade wears with time, in order for the cleaning blade to sustain the function only by means of the impregnation of the contact part of the elastic member with the curable composition as proposed, there is a need for reformation of the contact part by subjecting the contact part to impregnation for a long time to let the curable composition impregnate more inward to increase an impregnated region. However, through a long impregnation treatment, the elastic member undergoes a large swell with a solvent so that a deformation such as rolling occurs at the contact part and the cleaning blade will have an uneven contact with the image bearer, leading to a problem that a cleaning failure may occur.